There is a need for improved antiparasitic agents for use with mammals, and in particular there is a need for improved insecticides and acaricides. Furthermore there is a need for improved topical and oral products with convenient administration and which contain one or more of such antiparasitic agents which can be used to effectively treat ectoparasites, such as insects (e.g., fleas, lice, and flies) and acarids (e.g., mites and ticks). Such products would be particularly useful for the treatment of companion animals, such as cats, dogs, llamas, and horses, and livestock, such as cattle, bison, swine, sheep, and goats.
The compounds currently available for insecticidal and acaricidal treatment of companion animals and livestock do not always demonstrate good activity, good speed of action, or a long duration of action. Most treatments contain hazardous chemicals that can have serious consequences, including lethality from accidental ingestion. Persons applying these agents are generally advised to limit their exposure. Pet collars and tags have been utilized to overcome some problems, but these are susceptible to chewing, ingestion, and subsequent toxicological affects to the mammal. Thus, current treatments achieve varying degrees of success which depend partly on toxicity, method of administration, and efficacy. Currently, some agents are actually becoming ineffective due to parasitic resistance.
Isoxazoline derivatives have been disclosed in the art as having insecticidal and acaricidal activity. For example, WO2007/105814, WO2008/122375, and WO2009/035004 recite certain alkylene linked amides. Further, WO2007/075459 discloses phenyl isoxazolines substituted with 5- to 6-membered heterocycles. WO2011/101229 discloses certain dihydrofuran derivatives as antiparasitic agents. However, the citations do not exemplify a dihydrofuran substituted phenyl azetidine, nor does the prior art indicate that such compounds would be useful against a spectrum of parasitic species, regardless of morphological lifecycle stages, in animals.
Despite the availability of effective, broad spectrum antiparasitic agents, there remains a need for a safer, convenient, efficacious, and environmentally friendly product that will overcome the ever-present threat of resistance development.
The present invention overcomes one or more of the various disadvantages of, or improves upon, the properties of existing compounds. In particular the present invention develops new isoxazoline substituted phenyl azetidines which demonstrate such properties.